SANTA CLARA, Calif. >> Even Peyton Manning realizes he’s ready for the regular season. Or at least darn close.

Manning threw a 17-yard touchdown pass to Julius Thomas and dominated in his two series, leading the Denver Broncos past the San Francisco 49ers 34-0 on Sunday to spoil the NFL debut at sparkling $1.2 billion Levi’s Stadium.

“It’s been a good start. That’s all it is, though,” Manning said. “We’ve still got some things we have to improve on.”

The 38-year-old Manning, beginning his 17th season after throwing for an NFL-record 55 touchdowns last year, completed 12 of 14 passes for 102 yards and a 120.8 rating. He was 8 for 8 on Denver’s second drive, then backup Brock Osweiler took over and threw for a score and led another touchdown drive in a preseason matchup of the past two Super Bowl losers.

Colin Kaepernick went 5 for 9 for 39 yards in his two series before a sellout crowd at the team’s flashy new digs in the heart of Silicon Valley. Major League Soccer’s San Jose Earthquakes beat the Seattle Sounders in the stadium’s first sporting event Aug. 1.

Demaryius Thomas had three catches on Denver’s opening drive, including a 20-yard gain. That gives Thomas 10 receptions for 89 yards in Denver’s two victories against the NFC West’s powerhouses, the Super Bowl champion Seattle Seahawks and San Francisco.

“Coming off last year, losing the Super Bowl like we did, coming into OTAs I think everybody had a different mindset,” Demaryius Thomas said. “You can see it with older guys, new guys. Our main thing was going out and being able to convert, and as a defense stop guys. If we’re going to be stopped, we’re going to stop ourselves.”

C.J. Anderson ran for a 1-yard TD, while Matt Prater kicked a 26-yard field goal and Mitch Ewald added a late 22-yarder. San Francisco’s typically spot-on Phil Dawson sailed two long kicks wide right.

Denver did it on defense, too, getting two interceptions and a fumble recovery and a goal-line stand to end the game. The Broncos recovered another fumble on special teams.

“It was a great moment for our defense,” defensive lineman Marvin Austin said. “It’s real hard to put up a goose egg in a preseason game.”

The 49ers lost safety Antoine Bethea to a concussion early in the second quarter. He was able to walk off on his own, but later left for the locker room.

Denver linebacker Lamin Barrow limped off early in the second half with a lower leg injury, then the Broncos lost tight end Gerrell Robinson to a knee injury.

As San Francisco struggled in all phases, tens of thousands of fans made their way out midway through the third quarter — certainly helping to alleviate traffic concerns. The 49ers ended a four-decade run at Candlestick Park last season.

“We have to tighten this down fast,” coach Jim Harbaugh said. “We have work to do, there’s no doubt about it.”

Two key members of San Francisco’s offense made their first appearances of the preseason, with Frank Gore running for 9 yards on the first of his two carries. Wide receiver Michael Crabtree also appeared as defensive stars Patrick Willis and Justin Smith got the day off.

Broncos cornerback Kayvon Webster missed the game after spraining an ankle during Saturday’s practice. Denver already was thin as Chris Harris Jr. returns from tearing his left anterior cruciate ligament during the playoffs.

Kaepernick had his chances during his brief stint on the field.

On third-and-4 from the 37 the first drive, Kaepernick barely overthrew Brandon Lloyd in the end zone. Dawson then missed his first field goal attempt in the new stadium, sending a 55-yarder wide right. He missed wide right again from the other end on a 44-yarder late in the first half, and these weren’t in the unpredictable elements of Candlestick.

The 49ers are scoreless in their last seven quarters and have been outscored 57-3 this preseason. They lost 23-3 at Baltimore on Aug. 7.

“It’s the preseason, but it all means something,” left tackle Joe Staley said. “Scoring points is the name of the game, and we haven’t done it. … It will be a real test this week to see how we rebound from this.”